Method of making composite metal



March 10, 1942. T. B. cHAcE METHOD OF MAKING- COMPOSITE METAL I gauge and then Patented Mar. 10, 1942 2,275,585 METHOD or MAKING oomrosrrn METAL Thomas B. Chace, Winnetka, Ill., assignor to Clad Metals Industries, Inc., Chicago, 111., a corporation of Illinois Application October 8, 1937, Serial 1 Claim.

of machining the facing metal surfaces before rolling into strips, sheets, structural shapes, and the like.

It is well known to form a double composite ingot by locating two slabs of non-corrosive facing metal in the center of a mould and then pouring backing metal, such as plain steel, to fill the mould and form a bond with the facing metal.

and the edges and ends are two composite slabs or sheets, each having a corrosion resisting facing and a This method is not workable when using combinations of metals .that have different melting temperatures particularly when The resulting pile is then rolled to the desired thickness the facing metal or alloy, such as copper or one melting point metal.

that can be produced due large mass of backing metal, when poured around the facing inserts, does not radiate heat fast enough to prevent melting of the inserts.

It is common non-ferrous rolled faces between successive rolling operations. That is, a cast billet is rolled to a semi-finished overhauled, such as by scalping or milling to remove blisters and other surface imperfections. The resulting product is then rerolled to finish gauge. This is necessary in order to secure the desired to the fact that the facing of non-corrosive metal, such as any of the non-ferrous metals or the so-called stainless steels, in that the clad slabs made by steel mill practice are much larger and can not be readily overhauled by ordinary brass or coppermill methods. One object of the present invention, therefore, is to provide a simple and cheap means of surface overhauling on clad metal products.

The object of my invention, generally stated, is to provide for simultaneously making two composite metal slabs in a manner in which the facployed than heretofore and in which the surfaces of the facing metal are at once suitable for subsequent working. Another object of my invention is to provide a mposite slab as an integral body with a layer as to the size of ingot of facing metal between two layers of backing metal and then cut through the layer of facing ready for subsequent working as a result of the cutting operation.

Other objects of my invention will, in part, be obvious and in part appear hereinafter.

My invention,.accordingly, is disclosed in the embodiments thereof shown in the accompanying drawing, and it comprises features of construction, combination of elements, arrangements of parts, and method steps which will be in the constructions hereinafter set forth, and the scope of the application of which will be indicated in the appended claim.

For a more complete understanding of the nature and scope of my invention, reference may be had. to the following detailed description taken in connection with the accompanying drawing, in which:

Figure l is a view in top plan, of the mould construction that is employed in practicing my invention;

Figure 2 is a sectional view taken along the line 22 of Figure 1, and showing the cladding metal in the mould space provided therefor;

Figure 3 is a sectional view, taken along the line 3-3 of Figure 1, showing in more detail one form of mould strip;

Figure 4 is a vertical sectional view of another mbodiment of mould construction that may be employed in practicing my invention; and

Figure 5 is a sectional view taken along the line 5-5 of Figure 4 showing more clearly the provision of two mould strips, the bottom of the mould being closed by the sand of the casting flo'or.

Generally speaking, my invention resides in the casting of a facing metal or alloy between, two

the drawing, in carryspace between provided;

; ducing atmosphere.

'metal which forms provide 2 in the composite slabs. The inner welding surfaces l3 and ll of the slabs'lfandl2 are thoroughly' cleaned, as by sand blasting or pickling, so that they will be free from oxides. They are then arranged in spaced-apart'refation with the:

surfaces 13 and/M forming opposite walls of a mould space which is twice the thickness plus the cutting loss of the desired proportional cladding on one sheet. The sides and bottom'of the the slabs H by a mould strip, shownjgenerall'y at Hi, to provide a liquid-tight mould capable of retaining molten metal at high temperatures. It willbe observed that the mould strip l comprises side members I6 and I1 and a bottom member l8, Figure 3. -It will and bottom members may be formed by individual strips or that they may be formed by one continuous strip. Preferably they are formed of relatively thin steel strip material and are welded, as indicated at l9, along the adjacent surfaces of thebacking slabs II and I2. By this construction, a liquid-tight mould is provided that is relatively strong and it may be moved about as desired'bya crane. At the same time the backing slabs H and I2 are securely held in the desired spaced-apart relation so that this insures that the desired thickness of facing metal will be The mould assembly, as shown in Figure 1. is then preheated to welding" temperature under conditions which exclude atmosphere from "the welding surfaces l3 and M. This may be done either by covering thewelding/surfaces H and N with a suitable flux or by preheating in a re- When the mould assembly has been properly preheated,- the mould space between the welding surfaces l3 and I4 is .illed with molten facing an integrally diffused bond with these welding surfaces of the backing slabs H-"and' l2. The facing metar LallosLmay be formed Lcopper or copper alloys.

After the molten facing metal has been poured into the mould space, the entire assembly is allowed to cool to room temperature. In-order to the two composite slabs, the layer 20 of facing metal, as shown in Figure 2 of the drawing, may be cut, as by a saw,'along the line 2|, thereby leaving a portion of the facing metal integrally bonded to each of the backing slabs H and '12. It will be obvious that the surfaces of the resulting layers of facing metal formed by the saw cut will be free from imperfections and that, assuming that or the like, no further cleaning or machining operations are necessary in order to provide the desired finished surfaces suitable for subsequent working of the composite slabs into sheets, strips, structural shapes, and-the like. I have found that, by machining or cutting through the center of the resulting casting or through the center of the facing metal, better surfaces are provided than by merely machining off a thin skin from slabs cast in a conventional mould.

If the pile, as shown in Figure 2 of the drawing, is of substant'lalthickness, it may be desirable to refine thegcast facing metal structure before the machini g or cutting operation is per- This may be accomplished by hot rolling and subsequently machining formed. the entire assembly or sawing centrally through the pile to provide the'two composite slabs.

and I2 are closed off be understood that .these side;

there are no slag inclusions It will be obvious that the foregoing steps may be departed from to suit the particular combination of materials being processed or the available equipmentwithout departing from my invention. For instance, the mould space may be filled with slag or flux material which has a low specific gravity and a comparative low fusing temperature. This will protect the welding surfaces l3 and H during preheating of the mould and is readily displaceable by the facing metal when it is poured. The mould may be filled with solid facing metal, such as cast inserts. or scrapped irregular pieces, ma 'ng up the proper weight,

the top may be covered with a flux or slag, and

while the mould is being brought to welding temperature.

As shown in Figures 4 and 5 of the drawing, the bottom member l8 may be omitted and the bottom of the mould space may be closed by the sand floor 22 of the foundry. The mould formed by the backing slabs H and I2 and the side members l5 and I1 may be preheated as described hereinbefore with the welding surfaces l3 and H suitably protected from oxidization. The mould is then placed upon the sand floor 22 of the foundry to close the bottom and the molten facing metal is then poured into the mould space as described. When the resulting pile has cooled sufficiently, the layer of facing metal may, be severed to provide the two composite slabs.

The mouldassemblyshown in Figure 4 can be preheated to welding temperature in a bath of viscous molten slag. When it has reached the desired temperature, it is removed-to the sand floor 22. Sufficient liquid slag clings to the welding surfaces 13 and M to exclude atmosphere while the assembly isbeing moved to the sand floorand until the facing metal has been cast.

I claim as my invention-n...

Method of producing a pair of metal slabs having a relatively thick steel backing and arelatively thincopperfacingiusionbonded to said steel backing suitable .-for,,,reduction by rolling into thin composite stock which comprises forming a mould by disposinga painof flat steel backmg axes vertical and having welding fac s disposed in substantially parallel planes and sp, ced apart a distance substantially-twice zthe, the facing to'be formed on each slab to form a mould space between the slabs. cleaning the welding faces of the slabs, welding sheet stock to the sides of the steel slabs to hold the slabs in fixed spaced relation and to form lateral closures for the mould space between the slabs, preheating the mould including the slabs, pouring molten copper into the mould space of the preheated mould, allowing the copper to solidify, and cutting through the mould and the cast copper in a. median plane between and substantially parallel to the welding faces to form two copper faced slabs the exposed copper surfaces of which are raw metal substantially free of impurities and working the slabs by rolling on said cut faces.

THOMAS B. CHACE.

slabs adjacent each other with their major thickness of p 

